Value of a Standardized Pharmacologic Stress Protocol with Orciprenaline to Assess the Hemodynamic Importance of “Mild” Coarctation of the Aorta

Objective: A gradient of ≤20 mm Hg is judged as good hemodynamic result after treatment of coarctation of the aorta (CoA). Many patients with “mild” or residual coarctation (ReCoA) present with left ventricular hypertrophy, hypertension or exercise induced hypertension and may require antihypertensive treatment indicating that the coarctation has some clinical relevance. During catheter investigation gradients are measured under sedation or even general anesthesia therefore not reflecting the clinical significance. We investigated the value of a pharmacologic stress protocol to assess the hemodynamic/clinical importance of the coarctation and the indication for therapy.

Method: Retrospective analysis of all patients with CoA and a pharmacologic stress protocol from 2007 until 2014. Measurement of the diameters of the aortic arch, the CoA site, and the aorta at the level of the diaphragm (AoDia) wasperformed. Invasive gradients were assessed at rest, after pharmacologic provocation and after interventional treatment.

Result: A total of 145 patients were detected, there were 46 female and 99 male patients, and the mean age was 12.4 years, weight 42.3 kg, height 142.6 cm. ReCoA after surgery was present in 109/145, previous catheter interventions were performed in 67/145 patients (balloon in 50, stents in 34). Initial pressure was at rest and under sedation in the ascending aorta (AoA) 104.8/60.3/78.6 (syst/diast/mean in mmHg) and in the descending aorta (AoD) 91.6/58.0/73.5, the maximal systolic gradient was 13.2 mm Hg at a heart rate of 89.8/min, the CoA diameter was 9.1 mm and the AoDia was 14.6 mm (ratio: 0.6). After orciprenaline provocation the heart rate increased to 142.8/min and the pressures changed to 110.2/42.3/66.2 (AoA) and 69.6/38.7/51.1 (AoD), the peak gradient increased to 41.0 mm Hg. Balloon dilatation was performed in 58 and stent implantation in 87 patients. The gradient changed to a mean of 9.1 mm Hg after repeat pharmacologic provocation at a heart rate of 137.8/min, the CoA diameter increased to 12.8 (ratio: 0.9).

Conclusion: Even so-called “mild” CoA or ReCoA may cause relevant obstruction with clinical importance that is evident under exercise. The pharmacologic stress protocol presented here can help to detect those patients requiring treatment by simulating the effects of exercise during sedation in the cath laboratory. Establishing a normal sized aorta (CoA/AoDia ratio > 0.9) completely relieves the exercise induced pressure gradients.